The pistons in internal combustion engines or compressors are generally provided with a set of piston rings the purposes of which are preventing, between pistons and cylinders, any leak of gas to the crankcase and of oil to the piston head.
The presently known piston rings of said set interfere in operation one with another and the assembly thereof does not insure completely the attainment of said purposes, each of said piston rings being incapable of playing its entire role.
The compression rings permit passage of the gas (blow-by) from the combustion or compression chamber to the crankcase, and the oil rings scrape in both directions, and thereby work against their purpose in the upward stroke of the piston.
Thus, their roles are not exactly fulfilled thereby resulting in difficult tuning, instabilities, insufficiences and uncertainties of operation.
Finally, all said piston rings are applied with substantial force against the cylinder and are heavy, which results in significant energy consumption by friction and inertia.
The closest known prior art of the present invention includes the following:
U.S. Pat. No. 2,893,797 shows a scraper ring comprising a skirt opened to the crankcase, consisting of tongues applied to the cylinder through the action of a compression ring mounted in the same groove acting by tipping over upon an angled extension of such tongues penetrating said grooves; but the tongues of this ring have no freedom of movement on the piston and application thereof against the cylinder which is rigid is not appropriate for an oil scraping operation which, to be efficient, must be flexible and of low friction.
U.S. Pat. No. 2,846,280 shows flat rings associated with plastic rings configured as either compression rings or scraper rings, but which do not comprise any means for providing them freedom of movement with the piston, or contributing to efficiency or reduction of friction.
French Pat. No. 826,487 shows compression rings composed of thin frusto-conical ring packs comprising retaining means to prevent their cuttings from overlapping each other and applied against the cylinder through deformation of their cones caused by wedging them into their groove; however, such arrangements do not ensure any increased tightness or reduced friction.
U.S. Pat. No. 2,262,311 which shows a flat compression ring formed with many slots therein regularly distributed on the full periphery of the ring; above all it claims characteristics of conformability permitting adaptation thereof to worn cylinders but does not afford any progress in tightness or reduced friction.
French Pat. No. 869,831 shows a compression ring composed of two flat uncut rings mounted to a piston with a dismountable head, equipped with an application spring with a great number of slots in contact with the cylinder obturated by blocking through two superposed rings; here too, with such rings the cutting clearances are obturated but no freedom of movement of the ring in its groove is ensured and the ring does not realize any particular performance in the domain of tightness and reduction of friction.
British Pat. No. 1,126,457 shows a spiral spring for assisting the application force of a conventional ring against the cylinder; such system is known to increase the tension in a conventional ring but does not supply any novel element in the technology of piston rings either relative to tightness or friction against the cylinder.
Related prior art also includes:
U.S. Pat. No. 3,759,148 issued Sept. 18, 1973 PA0 U.S. Pat. No. 3,831,952 issued Aug. 27, 1974 PA0 U.S. Pat. No. 3,656,766 issued Apr. 18, 1972 PA0 U.S. Pat. No. 3,840,182 issued Oct. 8, 1974 PA0 U.S. Pat. No. 2,893,675 issued July 8, 1975 PA0 U.S. Pat. No. 3,917,290 issued Nov. 4, 1975 PA0 U.S. Pat. No. 4,103,594 issued Aug. 1, 1978 PA0 French Pat. Appln. No. 81,13347 filed July 8, 1981 PA0 French Pat. No. 2,185,094 PA0 French Pat. No. 1,540,312 PA0 Gr. Britain Pat. No. 593,392